This script is for mod authors. It is quite simple to use and will create a fairly robust standalone installer for your mod, which will automatically detect the Warband folder and be easy for the end user of your mod to install. Additionally, the created installer executable will tend to be quite a bit smaller than a ZIP file of the same mod.
This script uses the Nullsoft Scriptable Install System (NSIS).

Be sure to view the readme file (readme_installer.rtf) for very detailed instructions on how to use this.

Examples of a default unchanged copy of this installer script in action:

Upgrade Instructions
If you are using an older version of this script and want to update to the latest version, that's pretty simple.
1. Download the newer version of the Mod Installer Script here, but only extract the Warband Mod Installer Script 2.3.nsi file.
2. Open your older installer script file and this new one you just extracted, and copy and paste the top section of the old file (all the way down to where you see "You probably shouldn't edit below this point", which is about 35 lines) over the top section of the new one.
That's it.

Change List
v2.3:

Support for new Data folder.

v2.2:

Since some people were still having it not detect Steam versions (possibly they don't have Steam installed properly or similar?), I've added in extra explicit checks for the default Steam installation path rather than solely relying on getting Steam's installation path from the Registry.

When version detection failed, it could end up displaying the installed version as "1.[X]"; this has been changed to "(unknown)"

v2.1:

Steam release version and path detection were glitchy; they should work fine now.

v2.0:

Initial release, based completely off of my previous mod installer script for the original M&B.

I hope it will work with all versions 'cause Warband updates allmost every week.

The methods for determining the installation path and the installed version haven't changed since the original Mount&Blade (stored in the registry, or in the case of Steam, the Steam pseudo-registry), so i don't think there's anything to worry about there.